The present invention relates generally to apparatus for use in treating proliferative tissue disorders, and more particularly to an apparatus for the treatment of such disorders in the body by the application of radiation.
Malignant tumors are often treated by surgical resection of the tumor to remove as much of the tumor as possible. Infiltration of the tumor cells into normal tissue surrounding the tumor, however, can limit the therapeutic value of surgical resection because the infiltration can be difficult or impossible to treat surgically. Radiation therapy can be used to supplement surgical resection by targeting the residual tumor margin after resection, with the goal of reducing its size or stabilizing it. Radiation therapy, or surgical excision followed by radiation therapy, is commonly used to treat spinal metastases. Metastases are tumors that have grown in a location that is remote from the site that the tumor started, and spinal metastases result from the spread of cancer cells into a patient""s vertebral column.
Radiation therapy can be administered through one of several methods, or a combination of methods, including external-beam radiation, stereotactic radiosurgery, and permanent or temporary interstitial brachytherapy. The term xe2x80x9cbrachytherapy,xe2x80x9d as used herein, refers to radiation therapy delivered by a spatially confined radioactive material inserted into the body at or near a tumor or other proliferative tissue disease site. Owing to the proximity of the radiation source, brachytherapy offers the advantage of delivering a more localized dose to the target tissue region.
For example, brachytherapy is performed by implanting radiation sources directly into the tissue to be treated. Brachytherapy is most appropriate where 1) malignant tumor regrowth occurs locally, within 2 or 3 cm of the original boundary of the primary tumor site; 2) radiation therapy is a proven treatment for controlling the growth of the malignant tumor; and 3) there is a radiation dose-response relationship for the malignant tumor, but the dose that can be given safely with conventional external beam radiotherapy is limited by the tolerance of normal tissue. In brachytherapy, radiation doses are highest in close proximity to the radiotherapeutic source, providing a high tumor dose while sparing surrounding normal tissue. Interstitial brachytherapy is useful for treating malignant brain and breast tumors, among others.
While devices exist for delivering radiation to treat metastases, there is still a need for instruments which can be used to provide brachytherapy to target tissue within specific areas of a human body, such as within a patient""s spine. In particular, a number of cancers, including spinal cancers as well as other thoracic cancers, can proliferate into a patient""s spine. At present, there are no devices configured for treatment of such proliferation, especially where the proliferation extends through more than one vertebra within the spine.
The present invention generally provides a brachytherapy system for treating metastases on and around a patient""s spinous process. In one embodiment, a brachytherapy device is provided having a catheter member including a proximal portion, a distal portion, and at least one lumen extending therethrough. The distal portion of the catheter member includes first and second branch members that are adapted to be positioned on opposed sides of at least one of a patient""s spinous process. The device further includes first and second elongate anchoring elements disposed on the first and second branch members. The device is adapted to receive a radiation source through the at least one lumen in the catheter to the first and second branch members for delivering radiation to tissue surrounding the at least one spinous process. The device can also optionally include at least one centering mechanism disposed on each of the first and second branch members. Each centering mechanism is effective to maintain symmetry of the first and second branch members with respect to a patient""s spinal column, and/or to receive a radiation source and to deliver the source to a treatment site.
The first and second anchoring elements are preferably adapted to be positioned between a spinous process and transverse process of at least one vertebral body, and to extend along a length of a patient""s spinal column, such that the first and second anchoring elements, when expanded, engage and anchor the first and second branch members between the spinous process and transverse process of at least one vertebral body. In an exemplary embodiment, the first and second elongate anchoring elements each have a length adapted to span a plurality of vertebrae.
In another embodiment, the first and second anchoring elements can be first and second outer expandable balloons, and each centering mechanism can be an inner expandable balloon. Each inner expandable balloon preferably has a size adapted to receive a predetermined amount of a fluid radiation source such that varying doses of radiation can be delivered along a length of the outer expandable balloon. More preferably, each inner expandable balloon is effective to position a radiation source at a predetermined distance apart from the first and second outer expandable balloon to provide a minimum absorbed dose for delivering radiation to tissue adjacent to the outer expandable balloons.
In yet another embodiment, a brachytherapy device is provided including an elongate catheter member having a proximal portion, a distal portion, an inflation lumen, and at least one source lumen. A plurality of inner centering mechanisms are disposed around the catheter member and are in communication with a source lumen. In use, the device is adapted to receive a radiation source to deliver radiation to tissue surrounding the device. The device can also optionally include an outer anchoring member disposed around the distal portion of the catheter member and in communication with the inflation lumen. The outer anchoring member is adapted to anchor the catheter member between a spinous process and transverse process of at least one vertebral body, and to extend along a length of a patient""s spinal column. The plurality of centering mechanisms are preferably disposed within the outer anchoring member and are effective to maintain symmetry along a length of the distal portion of the elongate catheter member.
In yet another embodiment of the present invention, a method for treating spinal metastases is provided. The method includes the step of providing at least one brachytherapy apparatus for delivering radioactive emissions. The apparatus has a catheter member having proximal and distal ends and at least one lumen extending therethrough, at least one anchoring element disposed proximate to the distal end of the catheter, and a radiation source disposable through the at least one lumen in the catheter for delivering radiation to the tissue surrounding the anchoring element. The method further includes the steps of intraoperatively placing at least one brachytherapy apparatus between a spinous process and transverse process of at least one vertebral body along a length of the patient""s spinal column, providing a controlled dose of radiation to tissue surrounding the apparatus, and removing the brachytherapy apparatus. The radiation source is preferably placed into the brachytherapy apparatus after placement of the apparatus between the spinous process and transverse process of at least one vertebral body, and is removed from the apparatus before removal of the apparatus.